Resting & Action Potentials

Question 1

What are the four important properties of neurones?

Answer 1

Excitability, signal integration & propagation, signal transmission, plasticity

Question 2

How were resting membrane potentials first studied?

Answer 2

Giant squid axon

Question 3

At rest, which side of the axon membrane is negative?

Answer 3

Inside

Question 4

What is the approximate resting potential of an axon?

Answer 4

-60mV

Question 5

What causes leak current?

Answer 5

Selective permeability of the membrane to potassium ions

Question 6

How are ion gradients maintained?

Answer 6

Ion pumps

Question 7

What does Na+/K+ ATPase do?

Answer 7

Uses energy to move 3Na+ out of the cell and 2K+ into the cell

Question 8

What does it mean for an enzyme to be electrogenic?

Answer 8

Generates a potential difference between the inside and outside of the cell

Question 9

What does ouabain poison block?

Answer 9

Na+/K+ ATPase

Question 10

In the Nernst equation, what is Ek?

Answer 10

Equilibrium potential of the ion (mV)

Question 11

In the Nernst equation, what is R?

Answer 11

Gas constant

Question 12

In the Nernst equation, what is T

Answer 12

Temperature (K)

Question 13

In the Nernst equation, what is z?

Answer 13

Valence of the ion

Question 14

In the Nernst equation, what is f?

Answer 14

Faraday constant

Question 15

What does the Nernst equation do?

Answer 15

Compare electrical and chemical gradients to determine the electrochemical gradient

Question 16

What can the Nernst equation be used to determine?

Answer 16

Direction of the ion at any given membrane potential

Question 17

What is the Goldman constant field equation used for?

Answer 17

Determining the direction of multiple ions at any given membrane potential

Question 18

In the Goldman constant field equation, what is Em?

Answer 18

Membrane potential

Question 19

What temperature does the Goldman constant field equation relate to?

Answer 19

37C

Question 20

What happens during depolarisation?

Answer 20

Vm approaches ENa, spike due to transient increase in PNa

Question 21

What happens during repolarisation?

Answer 21

Vm approaches EK, spike due to transient increase in K

Question 22

What was shown by Hodgkin and Katz?

Answer 22

K+ is more responsible for resting potential and Na+ is more responsible for action potential amplitude